


Those Pleasant Thoughts of His

by MarshmarrowSans



Series: Tumblr Requests [7]
Category: Undertale (Video Game)
Genre: Demisexual Sans, Ecto-Penis (Undertale), Established Relationship, F/M, First Time, Fluff, Fluff and Smut, Mafia Sans, Simultaneous Orgasm, Smut, Sub Sans, Virgin sans, We call him Shortie as a nickname haha, because he is 4 ft 3 in tall, dom reader, mafiatale
Language: English
Status: Completed
Published: 2017-12-06
Updated: 2017-12-06
Packaged: 2019-02-11 08:38:44
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,512
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12931620
Author URL: https://archiveofourown.org/users/MarshmarrowSans/pseuds/MarshmarrowSans
Summary: Thinking about you always brought him comfort, even in the darkest of times.  What could be better than that?Well...  how about acting out some of those more private thoughts?(Mafiatale Sans/Reader first time fluffiness~)





	Those Pleasant Thoughts of His

**Author's Note:**

> Someone requested Mafiatale Sans' first time with reader. How sweet! <3

There was all kinds of business to take care of in Shortie's day, all manner of things on his itinerary that he didn't want to put the effort into, as ever.  Passionately making out with you just outside the door to his bedroom was not one of them.  But hey, he wasn't complaining.

 

As your lips pressed to his teeth and stifled any of the words that might have otherwise been exchanged between the two of you, he nestled into the warmth of your body and became so enveloped in your presence that he could hardly remember how he got here.  He could hardly remember the exchange of gunfire the two of you had been involved in earlier that day.  He only remembered one thing about it-- the moment you picked up that dead gang member's pistol and the careful, calculating look of concentration on your face as you used it to cover him until he got to safety.  It was a moment of strength for you, a moment of self-reliance and one that reassured him that the two of you really were meant to be together, that you were in every way his equal, that he didn't have to lie awake at night torturing himself at the thought of you dying early because of the life your relationship with him dragged you into--

 

See, that was just what he was trying to get away from right now.  Those dreadful thoughts.  All he wanted to think about right now was you and him together, and that was easy with your heated breaths sending warm puffs of air against his nose and your bodies pressed as close together as they could be.  How could he think of the bad things when you let out a moan so soft he could barely hear it, when you whispered his name and caressed his cheek like you treasured him more than anything?  He felt like his soul was on fire.

 

He put his hand over the one you had on his cheek, and metaphorically drunk, perhaps, on the feeling of being together with you, he said to you what had been on his mind for a matter of weeks now.  "sweetheart, i, uh.  i know i haven't...  uh.  well i've been having...  you know."  The rest of it came out in a nervous, heated rush.  "i just thought for a really really long time that i didn't wanna have sex but lately i've been thinking a lot about trying it.  with you.  and the thought is really exciting.  like arousing exciting.  so it's all really confusing for me but i think i actually want to try it now?"  In a moment of tenderness that would've seemed uncharacteristic if you didn't know him as well as you did, he reached up and touched your cheek in just the same way that you were touching his.  The blush on his cheeks and the nervous look on his face were absolutely irresistible.  "is...  that okay?"  
  
You huffed out a laugh.  He could tell that you were nervous, too.  That made him feel even better about this, knowing that he wasn't alone in that regard.  "Wow.  I never thought I'd see the day that you asked me for sex first.  Of course it's okay.  As long as you're sure that you're not just doing it to make me happy, and that it's really something that you want--"  
  
"it is."  He was so quick to answer he almost cut you off.  At least you knew that he was certain.  "if it convinces you any, it's been something i've... ah..."  His voice softened, at the same time that his grip on you tightened.  "something i've been thinking a _lot_ about lately.  you know.  when i'm alone.  especially when my soul is going nuts over you."  
  
"...  Oh."  You covered your mouth and giggled.  However embarrassed you were, he was twofold.  He giggled too.  
  
"hehe.  yeah.  like i said.  it's been confusing for me.  but i want you to know, this right now?  it's feelin' like a moment of clarity."  He reached around you to turn the doorknob to his bedroom and opened it for the two of you.  You'd been there a few times now, enough times that you were able to walk backwards to his bed until the backs of your knees hit the mattress and you fell to a sitting position with Shortie on your lap.  But all those times before had mostly been only to cuddle, and just a few times to make out.  Now this old mattress was going to see some very, very new action.

 

You wondered if you were making some kind of history here, being a human and making love to a monster.  You hoped you'd see a future where that was looked on with bemusement and pride and not with disgust.

 

Shortie erased all thoughts of anything other than the two of you from your mind by cupping your cheeks in his hands and pressing his teeth to your lips.  There wasn't much he could do with his skeletal mouth, but there was something in the way that he held you and moved in your lap that conferred the same effect as any kiss with lips.  Your hands found plenty to do to keep busy while the two of you kissed, slowly and curiously, as if it were your first kiss and you were exploring that novel and wonderful feeling all over again.  You ran your hands firmly up and down his chest at first, just firmly enough to feel the subtle shapes of his ribs underneath the fabric of his suit and vest.  And ever the more bold one, you were the first to start unbuttoning his clothes.  He gave no protest, didn't even tense for a moment.  The two of you almost seemed to move as one: everywhere you moved your hands, he moved his arms out of the way at almost the same moment, and vice versa, like a well-rehearsed routine that you were performing for the very first time.

 

That wasn't too strange, though, that you seemed to always be on the same wavelength.  That was normal for a pair of soulmates like you two.

 

It took you a moment to realize that, while you were ready to remove his jacket and vest, he was still caught up in fondling you through your clothes.  He was preoccupied right now with running his thumbs over your nipples, almost curiously, as if he didn't quite know what they were.  That look of quiet concentration on his face made you wonder if that was the case, and if maybe he was forgetting that he was allowed to strip you naked now.  You got his attention by moving your next kiss from his teeth to the tip of his nasal ridge.  He looked at you in curiosity and wonder.  You looked back at him with a smoldering look of confidence that he wouldn't forget for the rest of his life as you slipped the straps of your dress over your arms and shrugged it down just enough to reveal your bare breasts to him.

 

He looked stunned-- more so than any typical human guy would upon seeing that.  You could tell he was struck with the same sense of awe that you felt yourself every time you caught a glimpse of some new detail of his bone structure.  It wasn't even a necessarily sexual kind of awe.  Though there was no denying that he was aroused at the same time, it was entirely a sense of intrigue and appreciation he felt upon seeing such a private part of your body exposed to him.  It made him so happy that he almost forgot to reciprocate.  Almost.

 

He became visibly more nervous when he looked down at himself.  That was when he finally hesitated, when he started to sweat a little and rub the palms of his hands on his pants to dry them.  He didn't know how to present himself to you.  He didn't know how to be attractive.  You couldn't blame him-- that wasn't exactly a priority in the life he led.

 

You gave him a reassuring smile and placed your hand on the center of his chest.  His soul was glowing there in a distinct blue heart shape underneath his dress shirt, so strongly that you could feel its magic warmth radiating to your fingertips.  It glowed like that around you a lot, and you'd always wondered what it would look like with no fabric to muffle it, just that sweet little soul of his enclosed in his bare ribcage.  You gave him a moment to catch on to your intentions, then slid your hand under his shirt to start pulling it up and over his head.  
  
"This okay?" you asked in a gentle whisper.  
  
"mmhmm..."  Shortie sighed, in excitement and in relief, at the way you stepped in to guide him.  This was one of the many things that he loved about you.  Every time he felt lost, you always knew just when to offer your assistance.  You were always so capable, so sure of yourself, it was the only thing that could put him at ease when he thought of baring his soul to you for the first time.  Still, his mind raced with the most terrible thoughts.  
  
What if you didn't like it?

 

What if the color wasn't as bright as it should be?

 

What if you looked at him and decided his body was just too weird for you?

 

What if you felt nothing but pity for him when you saw how battered and vulnerable his soul was?  What if...  
  
What if...  
  
His thoughts slowed to a stop when he focused on you again and all doubts were erased from his mind.  He'd never seen a smile so loving and so genuine, and what made it even more beautiful was the way it was cast in the pale blue light emanating from his chest.  Suddenly he didn't know why he'd been so nervous before.  You knew that he was damaged, and you still loved him just as much, scars and all.  And he loved you, too.  Sometimes he just had to remind himself to believe in that.

 

"Oh, Sans..."  The sound of his name on your lips-- his real name-- sent a pleasant shiver down his spine.  He waited for you to say something else, but instead you bowed your head and pressed kisses from the bottom of his sternum all the way to the top.  God, he could swear he could feel your kisses as if you were pressing them to his very soul...  He moaned, deep and soft, and as he leaned his weight into you, you yielded to it and ended up flat on your back on his bed, your dress still pulled down to just below your breasts, your beautiful hair spread out around your head like a halo, your hands on each side of his waist.  He didn't have too long to enjoy that view, though, because you decided to give him an even better one.  You rolled over to place you two in the center of the bed, and in the process, you ended up on top of him instead.

 

His excitement mounted.  The more you showed your enthusiasm for this, the more comfortable he felt.  He ghosted his hands over your chest for a moment, just long enough to admire the soft skin there and the goosebumps that rose under his phalanges when he touched you, before he started working your dress the rest of the way off.  He was almost expecting you to stop him at some point, to keep him waiting, but you didn't.  He admired every inch of you as it was slowly, beautifully revealed to him.  The curve of your waist.  Your belly button.  The curve of your hips.  And most surprisingly...  


Oh, stars, he thought you'd been wearing underwear.  He could feel himself blush like an idiot when he got your dress all the way down to your thighs and realized, so suddenly that it elicited a gasp, that you had nothing on underneath.

 

And he was no expert, but he could guess by how wet and swollen pink you were down there that you were ready for him.

 

At no point during this encounter, of course, did it escape your notice that he wanted you just as much.  He'd been paying no mind to it, far too focused on you, but his magic had long ago fashioned a convenient conduit for his upcoming union with you.  It glowed the same brilliant blue as his exposed soul but was, for now, still constrained to a bulge straining against the fabric of his pants.  But now that you were naked, he had no excuse not to join you in such a state of undress.

 

He stammered your name and placed his hands on your bare hips-- the soft, squeezable flesh there drove him _crazy_ \-- when you took a detour from unbuckling his belt to run your hand up and down his bulge.  You could already get a sense of its size and girth.  Your heart pounded and your mouth dried at the thought of it stretching you.  "Still okay?"  It seemed like a good time to ask.

 

"please..."  He shifted closer to you desperately, and even moved one of his hands over yours to hold it right where it was.  He looked up at you with the most pleading, desperate eyes you'd ever seen.  "please.  _more_."

 

How could you refuse a plea like that?  You couldn't help but kiss him; he looked so damn desperate for you that you had the urge to comfort him, and it was the best way you could think of to do that.  He kissed you back gratefully as if gulping down water on a hot day.  And when you resumed your ministrations, when you fit your hand around the shape of his cock and stroked him up and down in such firm, deliberate motions...  well, there was no gentle way of putting it.

 

He moaned like an absolute whore for you.

 

You loved the sound of that so much that you almost didn't want to stop, but still, the idea of him cumming inside you was still much more appealing than just having him cum on your hands.  After all that buildup, it was pretty important to you that you finally get around to having sex with him for the first time.  So after playing with him just long enough to cherish those beautiful, lewd noises streaming from his mouth, you slid his pants down and over his feet so that you could see exactly what his magic had produced for you.

 

To put it lightly, there was no doubt he was aroused.  It was of average length, maybe a little shorter, but you'd be damned if you'd ever seen a cock that stiff before.  You could only assume that its luminescence was an indicator of his arousal as well, because it glowed as bright and as warm as his soul.  You didn't realize just how long you were staring at it until he spoke up.  
  
"uh hey there.  'scuse me.  i didn't stare at your tits for this long, y'mind moving on?"  He could've come across as annoyed, if he didn't have the biggest smirk on his face as he said that.

 

"Oh!"  Now it was your turn to blush.  "Oh I'm sorry.  It's just...  nice."  
  
"thanks, pal.  made it m'self."

 

You exchanged a look.  Then you both laughed, not nervously, but whole-heartedly, as if he'd cracked one of his best jokes yet.  It was awkward...  but...  nice?  It was the best, most heartwarming kind of awkward you had ever experienced.  You waited for the laughter to die down a bit, then caught his mouth in another tender kiss.  He hummed a couple more chuckles against your lips, then quieted down completely, except for a long, relaxed breath.  It was a nice lull, just the lull you needed before you got to the main attraction.  You took the opportunity to say something important, while looking him in the eyes.

 

"Sans?  I love you."

 

Yes, you'd said that to each other at this point.  Several times.  But it still made his soul feel like it was going to explode into fireworks every time he heard it from you and got to say it in return.  He didn't think it would ever stop feeling that way.

 

"i love you too."  He didn't break eye contact...  not until he tried to guide his penis to your entrance and couldn't quite find it.  The head slid up and down your slit, which felt kind of nice, but was obviously not quite what he was going for.  "ehehe.  you ready?"  
  
"Shouldn't I be asking you that~?" you quipped.  "Yes.  I'm ready."

 

"me t-- aa _ahhh_! woo..."  His pleasured cry the moment you lowered yourself on to his cock trailed into more of a relieved sigh as he slowly entered further and eventually hilted in you.

 

"Awoooo~" you teased him in return, though you made yours sound more like a wolf howl, whereas his had genuinely been just an exclamation of surprise.  "Did I startle you?"

 

"nnh...  it's just...  damn, you're fuckin' tight."  He held you by the hips and let his head fall back.  "goddamn.  gimme a minute before i totally embarrass myself here."

 

A part of you wanted to be mean, wanted to do the exact opposite of that and pound him to a fast, intense first orgasm that would leave him reeling.  But that probably wouldn't be a very romantic outcome to his first time.  You restrained yourself and took the moment to lean down and press a kiss to his sweaty forehead.  
  
"Alright."  You smiled at him affectionately from there, admiring how cute he was when he blushed as much as he was right now.  "Take as long as you need.  You're doing amazing."

 

"heh.  you're not doing half-bad yourself, beautiful."  His hands roamed back a little, then a little more.  You wondered if he realized just how much he was groping your ass right now.  Not that you minded.  In fact, you reciprocated.  He didn't have much to grope, per se, but he had plenty of crevices to explore.  You lovingly trailed your fingers down his spine and curled them gently around his tailbone.  He practically whimpered from how good that felt.  "fuuuck...  ok, we can keep going.  but not too fast.  take it easy on me, eh?"

 

You chuckled and threaded your fingers through his ribs.  It would make a perfect place to grab on to him during lovemaking, you realized.  "Sure thing, sweetheart."  As he'd requested, you continued at a pace just fast enough to not be agonizing.  "...  Hey, um, you know you don't have to last super long on your first shot, right?"

 

"i know!"  He looked embarrassed.  "but i--...  mmmh..."  Your hips picked up the pace just a little bit.  He was having a hard time keeping his train of thought on the rails.  Your smooth, confident movements were hypnotizing.  But he still got out the rest of that thought.  "please don't make me disappoint you, doll.  i'm trying, i'm really, really tryin'..."

 

You smiled down at him sympathetically and didn't slow for a moment.  "Shhh.  Don't worry about that.  You could pop off this instant and I'd be nothing short of proud of you for doing what you've done so far."  You wrapped your arms around him, pulled him to a sitting position, and amped it up just a little more until you were bouncing enthusiastically on his lap.  He gasped, then exhaled hard enough to blow a stray strand of hair from your cheek, wrapped his arms around you and started trying to move his hips in time with yours.  You fell into a delightful rhythm together, wrapped up in each other's embrace.  You could feel his apprehension melting in your hands, could almost see his worries and stresses dissipating from his body at long last at your quiet reassurances.  You were proud of him.  So, so proud of him.  For letting himself be vulnerable, for giving something a shot that he never thought he'd want to try before, for going for it even though he was obviously worried about turning you off.  You wanted to tell him all of that, too.  But he looked like he wanted to say something, and you weren't going to interrupt him.  You waited patiently until he got it out, in panting, unsteady breaths.

 

"god.  you're so.  fucking.  beautiful," he growled on the last syllable, overwhelmed to the point of sounding almost _frustrated_.  "i don't--"  he nuzzled into your shoulder, and you accepted him gratefully there, stroked soothingly down the back of his skull.  His voice continued, muffled but intelligible.  "i never have and never could do anything to deserve you, y'know that, i know that, but fuck, you're my angel.  my angel.  my everything."

 

You hadn't expected him to be such a sweet-talker during sex!  But you weren't about to point that out and embarrass him.  Instead, you held him close to you and peppered his skull in kisses.  Neither of you slowed for even a moment.  In fact, you pushed him to go a little faster, and he responded, matching your pace in moments.  You were perfectly in sync again.

 

"There you go.  That's it," you whispered encouragingly.  "C'mon, Sansy, show it to me.  Show me that you're mine."

 

You could've sworn that you felt him start to pound into you harder at the mention of his name, and by the end of your sentence, the two of you were definitively going at it harder than any point before.  You were making the bed shake and creak.  Poor Shortie...  he was sweating buckets, panting to the point of wheezing, pushing himself further than he would go for the sake of anything else...  You pushed him on to his back before he made himself pass the fuck out with all the effort he was putting in, mounted him again, and continued at your own, brutal pace.  He cried out, and you weren't surprised.  You knew you were being a little rough with him, but he would tell you if you ever went too far.  Instead, he threw both his arms and legs around you with nothing short of absolute desperation.

 

"i'm yours!" he groaned.  "i _am_.  i'm yours.  i'm _all yours_.  fu-hu-huck!"  His fingers dug into your flesh so tightly that it was a little bit, excitingly, painful.  He was so far gone right now, you were having a hard time believing that he hadn't reached climax yet.  
  
"aha--!  ah--!  babe! 'mcumming!"  Nevermind, there it was.

 

You kept one hand on the bed to brace yourself and did your best to keep up the rhythm you had going while you let your other hand roam down to work on your clit.  You were close, too.  Extremely close.  So much that a few firm circles with your fingers were enough to catch you up to where he was, right on the edge and ready to let himself go.  You locked eyes with him, saw the love, anguish, and desperation there, all at once...  It was enough.  It was just enough.  That fire in you ignited into a total explosion.  
  
He must have seen something in your expression, too, because he flushed blue, all the way from his cheeks to his shoulders, and he was wracked with an intense orgasm of his own.  Neither of you cared much what you were saying anymore, it all felt so right-- each other's names, proclamations of love, cries of how good this felt, they all came streaming out in broken voices and they all sounded so right.  Somewhere in his small body, he found one last burst of energy, and he used it to slam his hips upwards into yours in sloppy, uncoordinated thrusts meant only to bury his cock as deep in you as it could go.  You didn't even realize just how much he was filling you with his cum until you began to slow down and you could feel some of it dribbling back out of you.

 

And you only realized how fucking _intense_ your love-making session had been when you pulled out, collapsed on top of him, felt the mutually rapid rising and falling of your chests, and listened to the labored breathing.  You were exhausted, and every inch of your skin felt hot.  You couldn't imagine how Shortie felt.  He was always much less physically fit than you.

 

You let a few minutes pass.  Something you loved about being with Shortie was that you never felt the need to fill the silence.  You could just be there together, wordless, and still enjoy each other's presence.  You didn't need to say it.  You both knew the sex had been amazing.  You both knew how much you loved each other.  Now was the time to show it, not say it.  And you did.  He stared at you with sleepy, half-lidded eyes and dim, hazy pupils while he ran his phalanges through your hair as gently as he could.  You passed the time running your hands over his bones, admiring how smooth and warm they were.

 

It took you a few minutes, long enough for your breaths to slow, but you were the first to find words to break the silence.  "...  Sans?  That meant... a _lot_ to me."

 

You caught a glimmer of hope and appreciation in his eyes.  "me too."  
  
"Yeah, but that's a given.  I mean, that was your first time, not to mention the fact that you weren't even totally sure you wanted to go through with it.  But you trusted me to help you through it without overstepping your boundaries."  You smiled at him.  It was one of those smiles that made his soul melt in his chest every damn time he saw it.  "Don't think for a second that I've overlooked how major that was for you.  Or that this was even marginally less special to me than it was to you."  
  
"heh, geez, you're gonna make me mmm..."  He didn't get to finish.  You kissed him too quickly, and he cupped your cheek to kiss you back.  You started to pull away to say something silly, but he didn't seem to want to stop kissing you.  He pulled you back in, and you let him.  He planted sleepy kisses not just on your lips, but on each of your cheeks, your nose, and your forehead, too.

 

His kisses became progressively gentler until finally, he fell asleep altogether with his teeth still pressed to your forehead.  But that was alright.  At that point, you had long since fallen asleep, too.

 

Who knew what tomorrow would bring?  But for the next several hours, at least, you would be right there next to each other, dreaming of a future together that became more and more real with each passing day.


End file.
